Lifting jack



0d. 14,1941. A JACIKSON 2,259,421'

, LIFTING JACK Filed March 27; 1959 AL Ex/s cv/(s 0N INVENTOR.

BY I I QUA M0/muy ATTORNEY.

Patented Oct. 14, 1941 PATENT OFFICE LIFTING JACK Alexis Jackson,Bayside, Y., assignor to Vadim S. Makaroff, New York, N. Y.

Application March 27, 1939, Serial No. 264,326

19 Claims.

My invention relates to lifting jacks and has particular reference tojacks for lifting automotive vehicles at one end in order to renderaccessible the under side of such vehicles for repairs, etc. Myinvention has further reference to pneumatic or air operated jacks.

In an ordinary pneumatic jack of this type the lifting power isfurnished by a motor consisting of an air cylinder with a piston, thepiston being pivotally connected to a frame or base of the jack, thecylinder being mounted on the lifting arms pivotally connected at thelower ends to the frame, the free ends of the arms being used forraising a vehicle. Such jacks have a disadvantage in that the cylindermust be mounted entirely `above the lifting arms as otherwise it willinterfere with their lowering to the ground. The high cylinder forms anobstruction for the end extension of a vehicle such as rear bumpers,trunks, etc., so that the jack must be sufliciently long to extend underthe axle while the cylinder remains outside the bumper or trunk. It isalso necessary to shift the cylinder as far as possible to the rear ofthe jack, thereby increasing the leverage and making necessary acorresponding increase inthe lifting force,i. e., diameter of thecylinder. The high cylinder, moreover, interferes with the work aroundthe lifted end of the Vehicle.

My invention has for its object, therefore, to provide a jack in whichthe air cylinder is placed horizontally so that the jack can be movedunder the rear bumper of an automobile. With the horizontal mounting ofthe cylinder it is possible to increase the stroke of the piston, sothat the cylinder can be correspondingly reduced in diameter, stillfurther reducing the height of the jack.` The horizontal mounting of thecylinder makes it possible to build the frame of the jack' around thecylinder, the latter Contributing to the stiffness of the frame so thatless metal is needed for the frame with a corresponding reduction in thetotal Weight of the device and its cost.

Another disadvantage of ordinary lifts is that the lifting force remainspractically constant while the arm is being raised, although the momentof resistance considerably varies, being the greatest at the start andrapidly decreasing as the arm approaches the vertical position. Itbecomes necessary therefore to provide an air cylinder of a relativelarge diameter as determined by the initial torque only. In my improvedlift I provide a mechanism whereby the leverage between the cylinder andthe lifting arm varies,

being the greatest at the start when the moment 55 rollers in such' amanner that the angle of the` surfaces varies with the raising ofthearm, being the smallest at the start. As a result, the arm 15Trepresents a leverfwith a variable position of its middle fulcrum, thelower" end of the arms having supporting rollers under the frame of thejack. The arm is therefore directly supported on the rollers, relievingthe strain from the rear por- 20' tion of the frame.

Still another object of my invention is to provide a locking mechanismfor the jack in order to retainlthearm in the raised position regardlessof the air pressure in the cylinder. I also 2.5provide an improvedmanual control mechanism, preferably operated by a pedal, for releasingthe locking device simultaneously withthe release of air from thecylinder when it is desired to lower the arm.

My invention is more fully described in the accompanying specificationand drawing in which-- Fig. 1 is a sectional elevationof my jack showingthe arms in theV rai-sed position, the lowered Bposition being shown indotted lines;

Fig. 2 is a top plan View of the same; Fig. 3 isa rear end view of thesame ;v My lifting jack consists of an air cylinder I mounted' Ona frameformed of two angle iron 4Q beams 2. The front ends of the beams supporta shaft 4 with supporting wheels 5 at the ends. Brackets 6 are mountedat the sides of the beams 2 for a transverse shaft 1 having rollers 8 atthe ends. The rollers engage inner sides of arms S 4 made of channelbars joined together at the mid'- dle by a bridge plate II). The lowerends of the arms are joined by a shaft II with wheels I2 at the ends.Tubular rollers I3 are provided on the shaft I I to facilitate thesliding movement of the 50 shaft under the beams 2. The arms are bent atthe middle so that their free ends occupy a low position indicated indotted lines in Fig. 1 when the arms are lowered. The wheels I2 recedeto the rear of the cylinder when the arms are lowered'as shown in dottedlines in Fig. 1. The

shaft I2 is also connected by links I4 with the ends of a cross-bar I5resting on the upper edges of the beams 2, rollers I6 being provided toreduce the friction at the points of contact. The cross-bar I5 isconnected at the middle by a bolt Il to the end of a rod I8 extendingfrom a piston I9 in the cylinder I. The rod I8 is made of two channelbars welded together at the edges.

A valve nipple 20 is provided for admitting compressed air into thecylinder, the valve being preferably of the type used with automobiletires. A pressure gauge 2I may be provided for indicating air pressurein the cylinders. provided at the sides of the beams 2 for removablehandles 23 for moving the jack.

The operation of my jack is as follows: y l

The front end of the jack is moved under the axle of a vehicle untilrecessed grippers or forks Sleeves 22 areV 24 on the ends of the armsregister with the axle.v I

An air hose (not shown) is then fitted on the valve nipple'Zii and theair is turned on. As the pressure in the cylinder builds up, the pistonwill be moved outward, "carrying the cross-bar I5 and pulling the VlinksIll.'v As a result, the shaft II will' bemo'ved forward, the wheels I2sliding on the floor. The resistance to thismovement is reduced by theprovision of the vtubular rollers I3 on the shaft II and by the factthat the load is supportedl on the ends ofthe arms near the front wheels5 so that a very small fraction of this load rests on the'rear wheels I2before the arms are sufficiently raised. The arms move on the rollers3', the edges of the channel bars of the arms forming cam surfacesinclined at a small angle tothe direction vof the pull so that arelatively `small force is required to raise the' arms. The arms,

Ywliilesliding over the 'rollers 8, are also rotatedv on the shaft I I,the rotation being relatively small at the'start. It is graduallyincreased, however, as the arms are being raised, until at the end thesliding movement almost disappears, being replaced by a simple rotationon the rollers 8. The leverage will be then also reduced, resulting in amore rapid movement of the lifting arm. The

torque of the load on the arm will be then correspondin'gly decreased,however, because of the A shortening of the distance between the freeends of the arms and the wheels 8. By properly selecting therelativedimensions of the moving parts Vit is possible to' obtain a practically'constant torque for the lifting motor.

A locking mechanism is provided in order to hold the arm in the raisedposition even if the air should escape from the cylinder. This mechanismcomprises a dog 25 keyed on a shaft 26 journaled at the ends inYthe-sides of the brackets 6. The dog slides over the upper side of therod 18 provided with, a series of rectangular holes .21. The dog, whenfalling in one of the holes, engages the front edge ofthe hole as shownin Fig.

1, thereby locking the rod and preventing its inward movement underpressure of the load on thearms 9. A fork'28 is also keyed on the shaft25 and is engaged 'at the lower end by a compression spring 29 therebyurging the dog against the rod AIii'. A mechanism is provided forreleasing the dog from the piston rod, consisting of a lever 30pivotally'supported on brackets 3| at the rear of the cylinder I andhaving a pedal 32. The end of the lever is connected by a bar 33 withthe end of the fork 21, the bar sliding between the shaft I IY and the'cylinder I', the rollers I3being spaced apartto provide room for-thebar 33. The dog 25 israised by stepping on the pedal 32, thereby turningthevlever 30 and moving the fork 28 against the pressure of the spring29. An air exhaust valve 34 is tted in the bottom of the cylinder andconnected with the lever 3i) in such a manner that the air is releasedfrom the cylinder when the pedal is depressed and the dog raised, thearms being then released for their downward movement under the load of avehicle.

It is understood that my jack may be further modied within the scope ofmy invention vas set forth in the appended claims.

I claim as my invention:

1. A lifting jack comprising a frame, lifting arms, means to slidablyand rotatively support the arms on the frame at their intermediateportions, means to support an object on the front 4ends of the arms,means to slidably support the rear ends of the arms, and means to movethe rear ends of the arms forward thereby causing the arms to slide andto rotate on the supporting means at their intermediate portions so asto raise the front ends of the arms.

2. A lifting jack comprising a frame, lifting arms, means to slidablyand rotatively support the arms on the frame at their intermediateportions, means to 'support an object on the front ends of the arms,means to slidably support the rear ends of the arms, and means to movethe rear ends of the arms forward thereby causing the arms to slide andto rotate on the supporting means at their'intermediate portions so asto raise the front ends of the arms, the arms being bent in themiddle soas to bring the front ends below the first-mentioned supporting meanswhen the arms are in the lowered position.

3. A lifting jack comprising a frame, lifting arms, means to slidablyand rotatively support the arms on the frame at their intermediateportions, means to support an object on the front ends of the arms,means to slidably support the rear ends of the arms on the ground, andmeans to move the rear ends of the arms forward thereby causing the armsto slide and rotate on the supporting means at their intermediateportions so as Vto raise the front ends of the arms.

e. A lifting jack comprising a frame, lifting arms, means to slidablyand rotatively support the arms on the frame at their intermediateportions, means to support an object on the front ends of the arms,means to slidably support the rear ends of the arms comprising rollersthereon adapted to slide under the frame, and means to move the rearends of the arms forward thereby causing the arms to slide and to rotateon the supporting means at their intermediate portions so as to raisethe front ends of the arms.

5. A lifting jack comprising a frame, lifting arms, means to slidablyand rotatively support the arms on the frame at their intermediateportions, means to support an object on the front ends of the arms,rollers on the rear ends of the arms adapted to slide in engagement withthe frame, and means to move the rear ends of the arms forward therebycausing the arms to slide and to rotate on the supporting means at theirintermediate portions so as to raise the front ends of the arms.

6. A lifting jack comprising a frame, lifting arms, means to slidablyand rotatively support the arms on the frame at their intermediateportions, means to support an object on the front ends of the arms, ashaft connecting the rear ends of the arms passing under the frame,wheels on the shaft for supporting the arms on the ground, rollers onthe shaft for supporting the frame on the shaft, and means to move therear ends of the arms forward thereby causing the arms to slideand torotate the supporting means at their intermediate portions so as toraise the front ends of the arms.

7. A lifting jack comprising a frame, lifting arms having cam portions',means to slidably and rotatively support thearms on the frame at theircam portions, means to support anfobject on` the front ends of the arms,means to slidably support the rear ends of the arms on vthe `ground, andmeans to slidably rotate the armson their cam supporting means and tomove the rear ends forward thereby raising thefrontends of the arms.

8. A lifting jack comprising a frame, lifting arms having cam portions,means to slidably and rotatively support the arms on, the frame at theircam portions, the supporting` means forming fulcrums for the arms, meansto support an object on the front ends of the arms, means to slidablysupport the rear ends of the arms on the ground, and means to rotate thearms on their fulcrums and to cause the rear ends to slidably moveforward thereby causing the arms to slide by the cam portions on thefulcrum points so as to raise the front ends of the arms.

9. A lifting jack comprising a frame, wheels supporting the front end ofthe frame, brackets in the middle of the frame, rollers rotativelysupported on the brackets above the frame, lifting arms at the sides ofthe frame, longitudinal grooves in the arms slidably engaging therollers, means to rigidly join the two arms together, means on the frontends of the arms for supporting an object, a shaft joining the rear endsof the arms under the frame, wheels on the ends of the shaft forsupporting the arms on the ground,`

means on the shaft supporting the frame, and means to move the shaftwith the rollers forward thereby sliding and rotating the arms on therollers for raising the frontends of the arms.

10. A lifting jack comprising a frame, wheels supporting the front endof the frame, brackets in the middle of the frame, rollers rotativelysupported on the brackets above the frame, lifting arms at the sides ofthe frame made of channelshaped bars facing each other with theirflanges, the flanges slidably engaging the rollers, a member rigidlyjoining together the arms, means on the front ends of the arms forsupporting an ob- `iect, a shaft joining the rear ends of the arms Igunder the frame, wheels on the ends of the shaft for supporting the armson theground, means on the shaft supporting the frame, and means to movethe shaft with the rollers forward thereby sliding and rotating the armson the rollers for raising the front ends of the arms.

11. A lifting jack comprising a frame, lifting arms having cam portions,means to slidably and rotatively support the arms on the frame at theircam portions, the supporting means forming fulcrums for the arms, meansto support an object on the front ends of the arms, means to slidablysupport the rear ends of the arms on the ground, a cross member slidablysupported on the front portion of the frame, bars hingedly connectingthe rear ends of the arms with the cross member, and means to move thecross member forward thereby moving forward the rear ends of the arms,causing the arms to slide and to rotate on the fulcrums thereby raisingthe front ends of the arms.

12. A lifting jack comprising a frame, lifting arms having cam portions,means to slidably and rotatively support the arms on the frame at theircam portions, the supporting means forming fulcrums for the arms, meansto support an object on the front ends of the arms, means to slidablysupport the rear ends of the arms on the ground, a cross member slidablysupported on the front portion of the frame, bars hingedly connectingthe rear ends of the arms with the cross member, a motor supported onthe frame, and means to move the cross bar by the motor, causing thearms to slide and to'rotate on the fulcrums thereby raising the frontends of the arms.

13. A lifting jack comprising a frame, lifting arms having cam portions,means to slidably and rotatively support the arms on the frame at theircam portions, the supporting means forming fulcrums for the arms, meansto support an object on the front ends of the arms, means to slidablysupport the rear ends of the arms on the ground, a motor on the frame,and means to rotate the arms on the fulcrums so as to raise the frontends of the arms by the motor while causing the rear ends of the arms toslide on the ground.

14. A lifting jack comprising a frame, a. cylinder horizontally mountedon the rear portion of the frame, lifting arms at the sides of theframe, means to rotatively and slidably support the arms at theirintermediate portions on the frame, means to support an object on thefront ends of the arms, means to slidablysupport the rear ends of thearms, a piston in the cylinder, a rod on the piston, operativeconnections between the rod and the rear ends of the arms, and means toadmit a fluid under pressure into the cylinder for moving the pistonwith the rear ends of the arms thereby raising the front ends of thearms.

15. A lifting jack comprising a frame formed of two bars, a cylinderhorizontally mounted on the rear portions of the bars and rigidlyjoining the bars together, lifting arms at the sides of the frame, meansto rotatively and slidably support the arms at their intermediateportions on the frame, means to support an object on the front ends ofthe arms, means to slidably support the rear ends of the arms, a pistonin the cylinder', a rod on the piston, operative connections between therod and the rear ends of the arms, and means to admit a fluid underpressure into the cylinder for moving the piston with the rear ends ofthe arms thereby raising the front ends of the arms.

16. A lifting jack comprising a frame, a cylinder horizontally mountedon the rear portion of the frame, lifting arms at the sides of theframe, means to rotatively and slidably support the arms at theirintermediate portions on the frame, means to support an object on thefront ends of the arms, means to slidably support the rear ends of thearms, a piston in the cylinder, a rod on the piston, means to slidablysupport the front end of the rod on the frame, bars connecting the rodsupporting means with the rear ends of the arms, and means to admit afluid under pressure into the cylinder for moving the piston with therear ends of the arms thereby raising the front ends of the arms.

1'7. A lifting jack comprising a frame, a cylinder horizontally mountedon the rear portion of the frame, lifting arms at the sides of theframe, means to rotatively and slidably support the arms at theirintermediate portions on the frame, means to support an object on thefront ends of the arms, means to slidably support the rear ends of thearms, a piston in the cylinder, a rod on the piston, operativeconnections between the rod and the rear ends of the arms, means toadmit a fluid under pressure into the cylinder for moving the pistonwith the rear ends of the arms thereby raising the front ends of thearms, means to lock the rod in the operative position with the armsraised, a pedal at the rear of the frame, and operative connectionsbetween the pedal and the locking means for releasing the latter Whenvthe pedal is depressed.

18. A lifting jack comprising a frame, a cylinder horizontally mountedon the rear portion of the frame, lifting arms at the sides of theframe, means to rotatively and slidably support the arms at theirintermediate portions on the frame, means to support an object on thefront ends of the arms, means to slidably support the rear'ends of thearms, a piston in the cylinder, a rod on the piston, operativeconnections between the rod and the rear ends of the arms, means toadmit a uid under pressure into the cylinder for moving the piston withthe rear ends of the arms thereby raising the front ends of the arms,means to lock the rod in the operative position With the arms raised, apedal at the rear of the frame, operative connections between the pedaland the locking means for releasing the latter When the pedal isdepressed, and means to release the uid from the cylinder when the pedalis depressed.

19. A lifting jack comprising a frame, a lifting member, means toslidablyand rotatively support the member at its intermediate portion,means to support an object on the front ends of the lifting member,means to slidably support the rear end of the lifting member, and meansto move the rear end of the lifting member, thereby causing the liftingmember to slide and to rotate on the supporting means at itsintermediate portion so as to raise the front end of the lifting member.

ALEXIS JACKSON.

